Idiopathic megacolon: clinical guidelines

List of Abbreviations

ACR – Association of Coloproctologists of Russia

BF – Biofeedback

GI – gastrointestinal tract

IM – idiopathic megacolon

MTV – maximum tolerated volume

RAPS – Russian Association of Pediatric Surgeons

RAIR – rectoanal inhibitory reflex

РКИ – randomized controlled trial

RP — radiopharmaceutical

TSH – thyroid-stimulating hormone

CNS – central nervous system

I-MTV – index of maximum tolerated volume

Terms and Definitions

Megacolon is dilatation of the colon or the entire large intestine.

Megarectum is dilatation of the rectum.

1. Brief information on the disease or condition

1.1 Definition of the disease or condition

IM is a chronic dilatation of the large intestine for which no clear etiological factor can be identified.

1.2 Etiology and pathogenesis of the disease or condition (group of diseases or conditions)

The etiology of IM is unknown, reflecting its designation as "idiopathic," i.e., developing from unknown causes. Currently, it is also unclear whether this condition is congenital or acquired. A number of domestic and foreign authors, especially pediatric proctologists, associate the development of megarectum with the habit of suppressing the defecation urge, lack of favorable environmental conditions for bowel evacuation, psychological problems, or as a response to excessive and forceful coercion of the child to defecate by parents [1, 2, 3, 4, 5].

Other researchers see the cause of bowel dilatation in damage to its receptor apparatus or afferent nerve pathways. As a result, rectal sensitivity to filling is impaired, and the urge to defecate arises only upon the accumulation of a large amount of stool in it [6, 7, 8].

Finally, a third group believes that the pathogenesis of IM/megarectum is related not so much to impaired sensitivity as to a marked decrease in the tone of the intestinal wall and a sharp impairment of its contractile ability, of neurogenic or myogenic origin [9, 10, 11].

1.3 Epidemiology of the Disease or Condition

The prevalence of IM is unknown, but overall it is a rare condition. In a retrospective analysis of 1,600 patients with constipation referred to the Royal London Hospital over a 10-year period, only 20 had radiological signs of megacolon/megarectum [12]. However, on the other hand, moderately severe forms of this condition often remain unrecognized, and according to some data, up to 11% of patients with refractory constipation may have megacolon [13, 14]. Furthermore, estimating the prevalence of megacolon is hampered by the lack of universally accepted diagnostic criteria for this condition.

1.4 Features of Coding the Disease or Condition

Other functional intestinal disorders (K59):

K59.3 – Megacolon, not elsewhere classified.

1.5 Classification of the disease or condition

There is no universally accepted classification of IM.

1.5.1 Classification found in English-language literature.

Usually, 3 types of megacolon are described depending on the localization of the pathologically dilated segment:

1. Idiopathic megacolon – dilation of the colon or a segment of it;

2. Idiopathic megarectum – dilation of the rectum;

3. Idiopathic megabowel – dilation of the entire large intestine, i.e., a combination of megacolon and megarectum [15, 16].

1.5.2 Classification of megacolon in adults proposed by G.I. Vorobyov [17]:

1. megarectum;

2. megacolon;

3. dolichomegacolon.

1.5.3 Classification depending on the extent of the affected segment:

1. megasigmoid – dilation of the sigmoid colon;

2. left-sided megacolon – dilation of the sigmoid and descending colon;

3. subtotal megacolon – involvement extending up to the splenic flexure;

4. total megacolon – dilation of the entire colon and cecum.

1.6 Clinical presentation of the disease or condition

IM is a rare condition manifesting as constipation, abdominal distension, and sometimes leading to complications such as volvulus and acute intestinal obstruction. IM may remain asymptomatic for a prolonged period.

2. Diagnostics, medical indications and contraindications for diagnostic methods

Criteria for establishing the diagnosis/condition:

The diagnosis of IM is established in two stages. At the first stage, the presence of megacolon/megarectum is confirmed, primarily based on contrast X-ray imaging of the colon (barium enema, computed tomography). At the second stage, all known intestinal and extraintestinal causes of megacolon are excluded.

For these purposes, it may be necessary to consult (receive examination and consultation from) other specialists, such as:

· an endocrinologist (B01.058.001 Initial appointment (examination, consultation) with an endocrinologist); a pediatric endocrinologist (B01.058.003 Initial appointment (examination, consultation) with a pediatric endocrinologist) (to rule out hypothyroidism, hyperparathyroidism, pheochromocytoma, multiple endocrine neoplasia);

· a neurologist (B01.023.001 Initial appointment (examination, consultation) with a neurologist) (to rule out organic CNS lesions);

· a psychiatrist (B01.035.001 Initial appointment (examination, consultation) with a psychiatrist); a pediatric psychiatrist (B01.035.003 Initial appointment (examination, consultation) with a pediatric psychiatrist) (to rule out psychogenic megacolon, assess the mental status of patients with a combination of idiopathic megacolon and hypochondria, asthenoneurotic syndrome, etc.);

· a rheumatologist (B01.040.001 Initial appointment (examination, consultation) with a rheumatologist) (to rule out systemic connective tissue diseases as a cause of megacolon) [17, 18].

2.1 Complaints and Anamnesis

The main complaints in IM are constipation and abdominal distension [19, 20]. Most patients have a long history of constipation. In the case of idiopathic dilation of the distal large intestine (isolated megarectum or in combination with megasigmoid), symptoms usually begin in early childhood. Furthermore, a combination of constipation with encopresis is very characteristic, unlike Hirschsprung's disease, in which constipation also appears in childhood, but encopresis does not occur. In patients with IM and normal rectal size, a tendency toward constipation in childhood and youth can usually be elicited; however, symptom manifestation more often occurs at an older age.

In some patients, over time, constipation is replaced by irregular stools and diarrhea combined with progressive abdominal distension, weight loss, and episodes of difficulty passing gas. Such an "acute" worsening of the condition sometimes serves as the reason for seeking medical attention. Another cause for the acute development of symptoms can be a complicated course of IM – bowel volvulus, most often of the sigmoid colon. This is characterized by the onset of acute abdominal pain, usually initially colicky, combined with abdominal distension and cessation of gas and stool passage.

However, a short disease history more often suggests a secondary nature of megacolon. In such cases, it is necessary first of all to rule out a bowel tumor or inflammatory stricture, as well as toxic megacolon as a complication of ulcerative or pseudomembranous colitis and pseudobstructive syndrome (Ogilvie syndrome). The latter may be suggested by a history of drug or medication use (anesthetics, muscle relaxants, antidepressants, etc.), as well as prior trauma, including surgical interventions.

When taking the medical history, it must be remembered that organic lesions of the central nervous system and endocrine disorders can be causes of megacolon. A history of travel to South America should raise suspicion of a parasitic etiology (Chagas disease).

2.2 Physical Examination

The general condition of patients with uncomplicated IM is usually not compromised. In cases of pronounced megacolon, examination and palpation often reveal abdominal distension, an obtuse costal angle, and thinning of the anterior abdominal wall. A reduction or disappearance of hepatic dullness due to the liver being displaced posteriorly by the dilated colon is characteristic. In patients with distal bowel dilation, the upper pole of a pelvic mass – a fecalith/fecal impaction in the rectal lumen – is often palpable above the pubic bone. Fecaliths may also be detected through the anterior abdominal wall in more proximal parts of the colon. The presence of fever, tachycardia, chills, nausea, vomiting, or peritoneal signs indicates secondary megacolon or a complicated course of idiopathic megacolon.

Examination of the perianal region and digital rectal examination allow, first of all, to rule out a neoplastic nature of megacolon or an obstructive nature due to anorectal atresia and stenosis. The presence of fecal traces on the perianal skin confirms encopresis, which is characteristic of idiopathic megarectum. Anal sphincter tone and voluntary contractions are usually preserved. Also typical for idiopathic megarectum, revealed upon digital examination, is dilation of the rectum immediately above the anal canal and the presence of a large amount of putty-like contents or a fecalith in it. In Hirschsprung's disease, unlike idiopathic megarectum, the rectal ampulla is usually empty and the perianal region is unchanged. However, in cases of IM without megarectum, examination and digital rectal examination do not reveal significant changes either.

2.3 Laboratory Diagnostics

There is no specific laboratory diagnostic test for IM. Laboratory diagnostic tests should be performed in patients during the preparation and planning of surgical intervention to rule out concomitant diseases and conditions, as well as when differential diagnosis is necessary.

2.4 Instrumental Diagnostics

Comments: There are no unified, universally accepted diagnostic criteria for megacolon. Bowel dilation can be so pronounced that it is detected already upon clinical examination, laparotomy, or plain abdominal radiography. However, more often the clinical picture of megacolon is not so striking, and making a diagnosis based on such signs is largely subjective and not always possible. The main method for detecting megacolon is radiological – measuring the width of the bowel lumen when tightly filled, usually with a barium suspension, under double-contrast conditions. Normal values were obtained in two major X-ray morphometric studies and proved comparable except for the width of the rectum [18, 21] (Table 1).

Table 1. Normal width of the lumen in various parts of the large intestine.

Discrepancies in normal rectal diameter values between the two studies are likely due to differences in the testing methodology. Indirect confirmation of this is the fact that the upper limit of rectal width in healthy volunteers according to defecatory proctography was 8.3 cm [22]. Given the standardization of the double-contrast barium enema methodology in the Russian Federation, it is recommended to use parameters obtained by domestic authors. A diagnosis of megacolon is established if the lumen width of any part of the colon exceeds the specified values. Thus, if the maximum rectal diameter in any projection exceeds 8.5 cm, megarectum is diagnosed. A sigmoid colon width of more than 6 cm serves as the basis for diagnosing megasigmoid. Additionally, a number of authors point to the potential advantage of using CT colography with standardized pressure-controlled gas insufflation into the bowel lumen for a more accurate diagnosis of megacolon [19]. However, given the lack of studies on normal large intestine dimensions for this technique, its use to confirm a diagnosis of megacolon is currently impractical. Barium enema is also performed to assess the extent of IM and for differential diagnosis with Hirschsprung's disease [23, 24]. A radiocontrast examination is necessary for the differential diagnosis of IM and Hirschsprung's disease. Hirschsprung's disease is characterized by a sharp boundary between the dilated colon and a relatively narrowed distal aganglionic segment of varying length (most commonly the rectum, possibly involving part of the sigmoid) [23, 24]. In IM, either the rectum dilates immediately from the anal canal, or there is a gradual transition from a normal-sized rectum to a dilated sigmoid colon.

Comments: anorectal manometry includes the study of the rectoanal inhibitory reflex (reflex relaxation of the internal sphincter in response to increased pressure in the rectum). The absence of RAIR is a reliable diagnostic criterion for Hirschsprung's disease with a sensitivity of 70–95%. In IM/megarectum, RAIR is preserved, although its threshold may be significantly elevated due to increased rectal volume.

2.5 Other Procedures

Comments: a Swenson biopsy is the excision of a full-thickness section of the rectal wall followed by pathomorphological examination of the rectal biopsy (surgical) material (A08.19.001.002 Pathomorphological examination of rectal biopsy (surgical) material using immunohistochemical methods). The need for this invasive procedure arises during the differential diagnosis of IM and Hirschsprung's disease when contradictions exist between anorectal manometry data, immunohistochemical findings, and the radiological picture. Detection of aganglionosis of the myenteric and submucosal nerve plexuses is reliable confirmation of Hirschsprung's disease. It should be borne in mind that the zone of physiological hypo- and aganglionosis can extend up to 5 cm proximal to the dentate line [27]. To avoid a false-positive result, it is recommended to perform the biopsy by excising a full-thickness 1 cm wide flap along the posterior wall of the rectum from the dentate line with a length of at least 6 cm.

3. Treatment, including drug and non-drug therapies, diet therapy, and pain management

In uncomplicated IM, treatment is conservative in the majority of cases. Currently, there are no conservative methods that can achieve normalization of the colon lumen width. Even with complete symptom relief, the bowel lumen width does not change significantly. The goal of treatment is to select an effective and patient-convenient bowel emptying regimen, and to relieve or alleviate symptoms of abdominal discomfort. The need for surgical intervention arises when complications develop or when there is a high risk of them, and when conservative treatment methods are ineffective or poorly tolerated by the patient.

3.1 Conservative Treatment

3.1.1 Uncomplicated megacolon

Conservative treatment of patients with IM is fundamentally no different from the therapy of chronic slow-transit constipation. As a first step, a high-fiber diet and dietary fiber are prescribed, combined with an increased fluid intake and increased physical activity. At the same time, patients should be warned that dietary fiber does not have an immediate laxative effect. The treatment effect appears within 3–4 weeks.

Comments: prescribing dietary fiber does not always lead to improvement. Moreover, the condition of patients with megacolon on a high-fiber diet may even worsen due to increased flatulence and a feeling of heaviness in the abdomen.

Comments: the main representatives of this group of drugs are herbal preparations, bisacodyl**, sodium picosulfate, etc. They have a prokinetic effect, increase intestinal secretion, and decrease absorption. It should be noted that a significant number of both domestic and foreign authors consider long-term use of this group of drugs dangerous due to their damaging effect on the intramural nervous apparatus and the suspected carcinogenic effect [28, 29, 32, 33, 34, 35, 36, 37]. However, the degenerative changes in the nerve plexuses detected by authors in patients with persistent constipation may not be the consequence of long-term laxative use, but the initial cause of delayed transit. Furthermore, results obtained in animal experiments have not been confirmed subsequently by other researchers using more modern methods and equipment [38, 39]. In vitro and animal experiments have also shown that stimulant laxatives possess a carcinogenic effect [40]. However, ultra-high doses of laxatives were used in that study. S.A. Muller-Lissner et al. (2004), based on a broad analysis of literature, including controlled studies, conclude that currently used laxatives do not increase the risk of colorectal cancer even with multi-year use [41].

3.1.2 Complicated megacolon

3.2 Surgical Treatment

3.2.1 Megacolon

• In patients aged 18 years and older with megacolon and normal rectal diameter and function who require surgical treatment, it is recommended to perform a colectomy with ileorectal anastomosis (A16.18.030.013), or laparoscopically assisted colectomy with ileorectal anastomosis (A16.18.030.011), or laparoscopic colectomy with ileorectal anastomosis (A16.18.030.012), or subtotal colectomy with cecorectal anastomosis, or laparoscopically assisted subtotal colectomy with cecorectal anastomosis, or subtotal colonic resection with ascendorectal anastomosis (A16.18.030.016), or laparoscopically assisted subtotal colonic resection with ascendorectal anastomosis (A16.18.030.014), or subtotal colectomy with ileosigmoid anastomosis (A16.18.004.001) [15, 16].

GCR BLoE 3Level of Evidence B (Level of Confidence of Evidence – 3)

Comments: the formation of an ileorectal anastomosis is the most reliable option in terms of the risk of recurrent constipation. Dilation of the remaining cecum in ascendorectal/cecorectal anastomoses or the sigmoid colon in ileosigmoid anastomoses may lead to recurrent abdominal distension, impaired defecation and bowel emptying, constipation, and the need for additional, more aggressive resections [50, 51, 52]. On the other hand, preserving the cecum makes the development of diarrhea and incontinence less likely [53].

• In patients aged 18 years and older with megacolon and normal rectal diameter and function, as well as functionally preserved segments of the colon proximal to the dilated ones, it is recommended to consider open, laparoscopic, or laparoscopically assisted resection of the dilated bowel while preserving the anatomically and functionally intact proximal segments as an alternative to colectomy (A16.19.019 Resection of sigmoid colon; A16.19.019.001 Resection of sigmoid colon using video-endoscopic technologies; A16.19.019.002 Robot-assisted resection of sigmoid colon; A16.19.019.005 Nerve-sparing laparoscopically assisted resection of sigmoid colon; A16.18.015 Left hemicolectomy; A16.18.015.002 Left hemicolectomy using video-endoscopic technologies; A16.18.015.003 Robot-assisted left hemicolectomy) [54, 55].

Strength of recommendation 4 (Level of evidence – C).

Comments: compared with colectomy, the incidence of recurrent constipation and reoperations is higher after segmental resections (sigmoid resection, left hemicolectomy). However, with careful patient selection and assessment of the function of non-dilated colonic segments based on radiological or radionuclide intestinal transit studies, good functional results can also be achieved with limited resections [16].

3.2.2 Dilatation of the distal large intestine

• In patients aged 18 years and older with dilation limited to the distal large intestine (isolated megarectum or combined with megasigmoid) who require surgical treatment, it is recommended to perform open or laparoscopic nerve-sparing proctectomy with coloanal anastomosis (A16.19.021.012 Nerve-sparing laparoscopically assisted resection of rectum, or A16.19.021.011 Nerve-sparing intraperitoneal resection of rectum with precise dissection and preservation of pelvic autonomic nervous system elements, or A16.19.021.005 Low anterior resection of rectum, or A16.19.021.007 Abdominoanal resection of rectum with pull-through of sigmoid colon) or vertical reduction rectoplasty or longitudinal proctoplasty (A16.19.021.006 Low anterior resection of rectum with reconstruction of rectal ampulla) [15, 16, 43].

GPP CLOE 4Grade of Recommendation C (Level of Evidence – 4).

Comments: proctectomy with direct or pouch coloanal anastomosis is successful in 67%–72% of cases. However, it requires complete mobilization and removal of the rectum. Given its significant dilation and pronounced wall thickening with numerous large vessels, this is associated, on the one hand, with the risk of severe bleeding and, on the other hand, with the risk of damaging adjacent pelvic structures, particularly the pelvic nerve plexus, resulting in subsequent urogenital dysfunction [16]. Ideologically similar, vertical reduction rectoplasty and longitudinal proctoplasty are less radical and less traumatic alternatives to proctectomy. Both procedures aim to reduce the volume of the rectum.

Vertical reduction rectoplasty (VRR) involves mobilization of the left colon, including the splenic flexure. The sigmoid colon is transected at the level of the distal third using a linear stapler. The sigmoid and most of the descending colon are resected. Next, the rectum is mobilized along its posterior, lateral, and anterior walls down to the pelvic floor with transection of the "lateral ligaments". After rectal mobilization, a 100 mm linear stapler is applied in the vertical direction and frontal plane. Thus, after stapling and transection, the bowel is divided into anterior and posterior halves. The anterior half is then excised using a 60 mm linear stapler. The staple lines are reinforced with a continuous hand-sewn suture. Subsequently, an anastomosis is formed between the narrowed rectum and the proximal part of the descending colon using a circular stapling device. The procedure is completed by creating a diverting loop ileostomy [8].

In longitudinal proctoplasty, the reduction in rectal volume is achieved by transecting the rectum at a height of 8–10 cm from the external verge of the anal canal and excising a triangular flap from the anterior wall of the rectal stump, with the base at the resection level and the apex 2 cm above the upper edge of the anal canal. The resulting defect in the rectal stump wall is then closed longitudinally, and a circular colorectal anastomosis is formed. Depending on the extent of concomitant megacolon and the functional state of the non-dilated colonic segments, the colon is resected to the extent of a left hemicolectomy or subtotal colectomy. The procedure also ends with the creation of a diverting ileostomy [43].

With a success rate comparable to that of proctectomy (70%–80%), vertical reduction rectoplasty and longitudinal proctoplasty appear to be less traumatic and more favorable procedures from a functional standpoint. However, currently, experience with their use has been published from only two centers, and further studies on their efficacy and safety are needed.

3.2.3 Total megacolon combined with megarectum

• In patients with total megacolon and megarectum who require surgical treatment, it is recommended to perform open or laparoscopically assisted proctocolectomy with a small bowel reservoir and ileoanal anastomosis (A16.18.030.001 Colectomy with rectal resection, rectal mucosectomy, J-shaped small bowel pouch formation, and low mechanical ileorectal anastomosis, or A16.18.030.002 Laparoscopically assisted colectomy with rectal resection, rectal mucosectomy, J-shaped small bowel pouch formation, and low mechanical ileorectal anastomosis, or A16.18.030.005 Laparoscopically assisted colectomy with abdominoperineal rectal resection) [16].

GPP BLOE 3Grade of Recommendation B (Level of Evidence – 3).

Comments: the rate of satisfactory results is over 70%, however, the patient must be warned about the risk of reservoir dysfunction, which may manifest as frequent bowel movements and nocturnal incontinence. According to Hosie et al., the mean defecation frequency in 5 operated patients was 5 times per day, and three patients (60%) reported nocturnal incontinence [56]. Stewart et al. performed proctocolectomy with a J-pouch in 14 patients without complications. Twelve (86%) of them had a stool frequency of less than 7 times per day and did not suffer from incontinence, 1 patient noted "slight leakage", and another required graciloplasty for overt incontinence. However, subsequently, 4 patients (28.6%) underwent pouch excision and ileostomy due to persistent abdominal pain and bloating [57].

3.2.3 Creation of an intestinal stoma.

• If surgical treatment of IM / megarectum is necessary in patients with severe somatic status or those wishing to avoid the risk of complications associated with major surgery, it is recommended to create a diverting intestinal stoma (A16.18.007 Colostomy or A16.17.007 Ileostomy) [16].

GPP BLOE 3Grade of Recommendation B (Level of Evidence – 3).

Comments: stoma creation is a significantly less traumatic alternative to resection procedures. It may also be relevant when other surgeries have failed. It is recommended to form the stoma proximal to the dilated segments, and the patient should be warned that it may not relieve abdominal pain and bloating [16].

3.2.5 Surgical treatment of complicated megacolon

• If conservative attempts to resolve volvulus fail, urgent surgical intervention is recommended [18, 48, 49].

Level CLevel 5Level of recommendation evidence C (reliability level of evidence – 5).

Comment: if the bowel forming the volvulus is viable, detorsion is performed. If there are signs of compromised bowel blood supply, bowel wall perforation, and/or peritonitis, resection of the affected area is performed without primary anastomosis (A16.19.019.003 Obstruction resection of sigmoid colon or A16.19.019.004 Obstruction resection of sigmoid colon using video-endoscopic technologies or A16.18.016 Right-sided hemicolectomy or A16.18.016.001 Right-sided hemicolectomy using video-endoscopic technologies). Subsequently, after examination and clarification of the functional state of the remaining segments, reconstructive surgery is possible.

4. Medical Rehabilitation and Sanatorium-Resort Treatment

Specific rehabilitation measures for patients with IM are absent. If an intestinal stoma was formed during surgical treatment complicated by megacolon, medical rehabilitation measures are aimed at restoring the natural passage of intestinal contents through the gastrointestinal tract. All patients in whom an intestinal stoma (both temporary and permanent) was formed as a result of surgical treatment are recommended to have a consultation and follow-up by a stoma care rehabilitation specialist.

5. Prevention and Dispensary Observation

There are currently no specific prevention measures for IM. Prevention of the complicated course of IM, in particular the formation of fecalith, is to a certain extent the selection of an adequate bowel evacuation regimen using laxatives and enemas. If there is a history of bowel volvulus, elective surgery is recommended as a prevention of life-threatening complications.

6. Organization of Medical Care

Medical care, with the exception of medical care within the framework of clinical trials, in accordance with Federal Law No. 323-FZ dated November 21, 2011 (as amended on December 28, 2022) "On the Fundamentals of Protecting the Health of Citizens in the Russian Federation", and Government Decree of the Russian Federation No. 1968 dated November 17, 2021, "On Approval of the Rules for the Phased Transition of Medical Organizations to the Provision of Medical Care Based on Clinical Guidelines Developed and Approved in Accordance with Parts 3, 4, 6–9, and 11 of Article 37 of the Federal Law 'On the Fundamentals of Protecting the Health of Citizens in the Russian Federation'", is organized and provided:

1) in accordance with the regulations on the organization of medical care by types of medical care, approved by the authorized federal executive body;

2) in accordance with the care standards for the profile "coloproctology", which are mandatory for implementation throughout the Russian Federation by all medical organizations;

3) based on these clinical guidelines;

4) taking into account the standards of medical care approved by the authorized federal executive body.

Medical care for patients with IM is provided by coloproctologists, and in their absence, by surgeons and pediatric surgeons. Treatment of patients with IM can be carried out both on an outpatient basis and in a coloproctological hospital, or in a general surgical hospital if a coloproctological one is not available. Elective surgical treatment should be carried out in coloproctological departments where the full range of necessary diagnostic examinations is available. Emergency treatment of complicated IM is carried out in a specialized coloproctological hospital, or in a surgical hospital if not available. Hospitalization of patients can be carried out both on an elective and emergency basis.

Indications for emergency hospitalization:

· Complicated course of IM (colonic volvulus, intestinal obstruction by fecalith) when the complication cannot be resolved on an outpatient basis (endoscopic detorsion of volvulus, fecalith evacuation).

Indications for planned hospitalization:

· inability to perform diagnostic or therapeutic procedures on an outpatient basis;

· need for surgical intervention.

Indications for patient discharge:

· with sustained improvement, when the patient can continue outpatient treatment without detriment to health under the supervision of a coloproctologist, surgeon, or pediatric surgeon

· in the absence of indications for further inpatient treatment

· if it is necessary to transfer the patient to another medical institution

· at the request of the patient or their legal representative

· in cases of non-compliance by the patient with prescriptions or internal inpatient rules, provided this does not threaten the life of the patient or the health of others.

7. Additional Information

On the one hand, even effective conservative treatment carried out for several years does not lead to normalization of the bowel diameter. On the other hand, there is no reason to expect mandatory progression of IM or symptom progression. Therefore, if conservative treatment is effective, it is recommended to continue it as long as its effect persists or until all its options are exhausted. Regarding surgical treatment, a favorable outcome can be expected, depending on the situation and the scope of surgery, in 50-90% of cases. However, it must be borne in mind that surgery is primarily aimed at preventing life-threatening complications and relieving bowel evacuation disorders. Regarding symptoms of abdominal discomfort, the prognosis is much less definite. In addition, the surgery itself is associated with the risk of potentially health-threatening complications, both in the short and long term. The patient must be warned that the incidence of adhesive obstruction on long-term follow-up reaches 40-50%, and a succession of postoperative complications or failure of interventions performed may lead to the need for a permanent stoma [15, 16, 42].

Criteria for Evaluating the Quality of Medical Care

Quality assessment criteria for primary health care provided to adults and children with idiopathic megacolon

Quality assessment criteria for specialized medical care provided to adults and children with idiopathic megacolon

References

Appendix A1. Working Group Composition

All members of the working group are members of the Association of Coloproctologists of Russia. There is no conflict of interest.

Appendix A2. Methodology for Developing Clinical Guidelines

Target audience for these clinical guidelines:

1. Coloproctologists

2. Surgeons

3. Pediatric surgeons

4. Gastroenterologists

5. General physicians / Internists

6. General practitioners (family physicians)

7. Endoscopists

8. Mid-level medical professionals

9. Healthcare organizers

10. Expert physicians of medical insurance organizations (including when conducting medical and economic expertise)

11. Medical students, residents, postgraduates.

Table 1. Levels of Evidence (LoE) grading scale for diagnostic methods (diagnostic interventions)

Table 2. Scale for grading levels of evidence certainty (LEC) for prevention, treatment, and rehabilitation methods (preventive, therapeutic, and rehabilitative interventions)

Table 3. Scale for grading grades of recommendation (GR) for prevention, diagnostic, treatment, and rehabilitation methods (preventive, diagnostic, therapeutic, and rehabilitative interventions)

Procedure for updating clinical guidelines.

The mechanism for updating clinical guidelines provides for their systematic revision at least once every three years, as well as upon the emergence of new evidence-based medicine data on the diagnosis, treatment, prevention, and rehabilitation of specific diseases, or in the presence of justified additions/comments to previously approved clinical guidelines, but no more frequently than once every 6 months.

Appendix A3. Reference Materials

These clinical guidelines were developed taking into account the following regulatory legal documents:

1. Article 76 of Federal Law of the Russian Federation No. 323-FZ dated November 21, 2011, "On the Fundamentals of Public Health Protection in the Russian Federation", regarding the development and approval of clinical guidelines (treatment protocols) for the provision of medical care by medical professional non-profit organizations;

2. Order of the Ministry of Health of the Russian Federation No. 206n dated April 2, 2010 (as amended on February 21, 2020) "On Approval of the Rules for the Provision of Medical Care to the Population with Colonic, Anal Canal, and Perineal Diseases of Coloproctological Profile";

3. Federal Law of the Russian Federation No. 326-FZ dated November 29, 2010 (as amended on July 3, 2016), "On Compulsory Medical Insurance in the Russian Federation";

4. Order of the Ministry of Health of the Russian Federation No. 203n dated May 10, 2017 "On Approval of Criteria for Assessing the Quality of Medical Care";

Appendix B. Physician Action Algorithms

Appendix C. Patient Information

Idiopathic megacolon is defined as chronic dilation of the colon that is not associated with Hirschsprung disease and for which a clear etiological factor cannot be identified. Acute megacolon may be caused by a mechanical obstruction (tumor, inflammatory or ischemic bowel stricture), pseudo-obstruction syndrome, or severe inflammation (toxic megacolon as a complication of ulcerative or pseudomembranous colitis). Chronic colonic dilation can be caused by organic central nervous system disorders, including spinal cord injuries, as well as a number of endocrinological disorders. In addition, chronic megacolon is observed in adult Hirschsprung disease, anorectal malformations (atresia, stenosis), and certain infectious processes (Chagas disease). The diagnosis of idiopathic megacolon is established by ruling out both intestinal and extraintestinal known causes of colonic dilation.

Most patients with idiopathic megacolon have a long history of constipation. In cases of idiopathic dilation of the distal colon (isolated megarectum or combined with megasigmoid), symptoms usually appear in early childhood. A very characteristic feature is the combination of constipation with encopresis (fecal incontinence), unlike Hirschsprung disease, where constipation also presents in childhood but encopresis does not occur. In patients with idiopathic megacolon and a normal rectal size, a tendency toward constipation in childhood and adolescence can usually be elicited, but symptom manifestation typically occurs at an older age.

In some patients, constipation is eventually replaced by irregular stools and diarrhea combined with progressive abdominal bloating, weight loss, and episodes of difficult passage of gas. Such an "acute" worsening of the condition often prompts a visit to the doctor. Another cause of acute symptom onset may be a complicated course of idiopathic megacolon—volvulus, most commonly of the sigmoid colon. This is characterized by the onset of acute abdominal pain, usually initially cramping, combined with abdominal distension and cessation of gas and stool passage. If such symptoms occur, medical attention must be sought immediately. Delaying treatment can lead to life-threatening complications. With timely presentation, decompression and detorsion of the bowel can in most cases be performed endoscopically (using a colonoscope), thereby avoiding the need for emergency surgery.

The diagnostic protocol for idiopathic megacolon pursues two objectives:

1) identification of megacolon and its complications, and determination of the extent of the lesion;

2) exclusion of known intestinal and extraintestinal causes of its occurrence.

This requires a comprehensive range of diagnostic procedures, including laboratory, radiological, pathophysiological, and morphological research methods. In a significant number of cases, only the use of the full set of tests allows for differential diagnosis with other potential causes of megacolon and the formulation of appropriate management tactics.

Unlike Hirschsprung disease, in idiopathic megacolon, colonic dilation is not the result of a distally located zone of functional obstruction. Accordingly, there is no reason to expect mandatory progression of colonic dilation and clinical symptoms. Therefore, in most cases, the management of idiopathic megacolon is conservative. Unfortunately, there are no conservative methods that allow for the normalization of the diameter and functional state of the bowel. Even with successful symptom control, the caliber of the bowel lumen does not change significantly. Thus, the goal of treatment is to select an effective and convenient method of bowel evacuation for the patient and to alleviate symptoms of abdominal discomfort, difficulty with defecation, and encopresis. This typically involves regular enemas with a volume of 200–500 ml combined with various laxatives.

If treatment is effective, it should be continued as long as the effect persists or until all therapeutic options are exhausted. Idiopathic megacolon is a benign condition and does not pose an immediate threat to the patient's health and life on its own. Unfortunately, there is little hope of achieving an "excellent" result and complete normalization of the motor-evacuatory function of the bowel through surgery. Moreover, surgery itself carries the risk of potentially hazardous health complications, both in the short and long term. The incidence of adhesive intestinal obstruction in patients operated on for chronic constipation reaches 40–50% on long-term follow-up. Furthermore, a succession of postoperative complications or the failure of interventions may lead to the need for a permanent stoma. Therefore, the indications for surgical treatment are most often complications (recurrent volvulus, fecaliths, and fecal impactions causing intestinal obstruction) as well as a high risk of their development. Otherwise, it is preferable to adhere to conservative management.

Appendix G. Assessment Scales, Questionnaires, and Other Evaluation Tools

No.